The present invention relates to an intelligent color gamut management method and, more particularly, to an intelligent color gamut management method, which performs a saturation mapping and a luminance mapping separately according to a characteristic of a target device, which is to receive a color signal from a source device and has a different color gamut from that of the source device, thereby enabling the target device to represent a natural color image. 2. Description of the Related Art
Color reproducing devices such as monitors, scanners and printers use different color spaces or different color models depending on their respective utilization fields. For example, a color printer uses a CMY color space, a color CRT monitor or computer graphic device uses an RGB color space, and devices treating hue, saturation, and brightness use a HIS color space. Also, a CIE color space is used to define a ‘device independent color’ that is reproducible on any device. Representative examples of the CIE color space are CIE-XYZ, CIE L*a*b, CIE L*u*v.
The color reproducing devices may have different color gamut. The color space defines a color, i.e., defines a relationship between two different colors, whereas the color gamut defines a color reproducible range. Accordingly, if there is a discrepancy in color gamut between an incoming color signal and a color reproducing device reproducing the incoming color signal, the color reproducing device is required to perform a gamut mapping of properly converting the color signal and thus matching the different color gamuts to improve a color reproducibility.
General gamut mapping available for the different color devices converts a color space of an incoming color signal and then maps lightness and saturations without changing hues. More specifically, the color space of the incoming signal is converted from a ‘device dependent color space (DDCS)’ such as RGB and CMYK into a ‘device independent color space (DICS)’ such as CIE-XYZ and CIE-LAB. To accomplish this, the DICS is converted into LCH coordinates defined by hue, lightness, and chroma, and then a gamut mapping with respect to lightness and chroma is performed in a constant hue plane. Most frequently used gamut mappings are a method that maps chroma while maintaining lightness, and a vector mapping method that converts both lightness and chroma simultaneously. Various modified methods based on the two above-described methods are used.
The gamut mapping uses boundary information of color gamut to determine to what degree color signals match between two different color devices. Since the gamut mapping is generally performed in a constant hue plane in order to maintain constant hue, color gamut boundaries with respect to brightness and chroma are required for each color. However, in order to obtain the color gamut boundaries, a complicated calculation is required. If color gamut coordinates use a nonlinear function like CIE L*a*b and CIE L*u*v, a calculation to obtain a color gamut boundary becomes more complicated. Therefore, it is difficult to obtain color gamut boundary information in real time. Also, the color gamut boundary information is stored in a look-up table (LUT) or the gamut mapping itself is converted into 3D LUT. Accordingly, a memory for storing the LUT has to have a high storage capacity.